package http

import (
	"bytes"
	"errors"
	"fmt"
	"net/http"
	"path/filepath"
	"strings"
	"time"

	"github.com/mediocregopher/blog.mediocregopher.com/srv/http/apiutil"
	"github.com/mediocregopher/blog.mediocregopher.com/srv/post/asset"
)

func (a *api) managePostAssetsHandler() http.Handler {

	tpl := a.mustParseBasedTpl("post-assets-manage.html")

	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {

		ids, err := a.params.PostAssetStore.List()

		if err != nil {
			apiutil.InternalServerError(
				rw, r, fmt.Errorf("getting list of asset ids: %w", err),
			)
			return
		}

		tplPayload := struct {
			IDs []string
		}{
			IDs: ids,
		}

		executeTemplate(rw, r, tpl, tplPayload)
	})
}

func (a *api) getPostAssetHandler() http.Handler {

	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {

		maxWidth, err := apiutil.StrToInt(r.FormValue("w"), 0)
		if err != nil {
			apiutil.BadRequest(rw, r, fmt.Errorf("invalid w parameter: %w", err))
			return
		}

		var (
			path = strings.TrimPrefix(r.URL.Path, "/")
			buf  = new(bytes.Buffer)
		)

		err = a.params.PostAssetLoader.Load(
			path,
			buf,
			asset.LoadOpts{
				ImageWidth: maxWidth,
			},
		)

		if errors.Is(err, asset.ErrNotFound) {
			http.Error(rw, "Asset not found", 404)
			return

		} else if errors.Is(err, asset.ErrCannotResize) {
			http.Error(rw, "Image resizing not supported", 400)
			return

		} else if err != nil {
			apiutil.InternalServerError(
				rw, r, fmt.Errorf("fetching asset at path %q: %w", path, err),
			)
			return
		}

		http.ServeContent(
			rw, r, path, time.Time{}, bytes.NewReader(buf.Bytes()),
		)
	})
}

func (a *api) postPostAssetHandler() http.Handler {

	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {

		id := r.PostFormValue("id")
		if id == "" {
			apiutil.BadRequest(rw, r, errors.New("id is required"))
			return
		}

		file, _, err := r.FormFile("file")
		if err != nil {
			apiutil.BadRequest(rw, r, fmt.Errorf("reading multipart file: %w", err))
			return
		}
		defer file.Close()

		if err := a.params.PostAssetStore.Set(id, file); err != nil {
			apiutil.InternalServerError(rw, r, fmt.Errorf("storing file: %w", err))
			return
		}

		a.executeRedirectTpl(rw, r, a.manageAssetsURL(false))
	})
}

func (a *api) deletePostAssetHandler() http.Handler {

	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {

		id := filepath.Base(r.URL.Path)

		if id == "/" {
			apiutil.BadRequest(rw, r, errors.New("id is required"))
			return
		}

		err := a.params.PostAssetStore.Delete(id)

		if errors.Is(err, asset.ErrNotFound) {
			http.Error(rw, "Asset not found", 404)
			return
		} else if err != nil {
			apiutil.InternalServerError(
				rw, r, fmt.Errorf("deleting asset with id %q: %w", id, err),
			)
			return
		}

		a.executeRedirectTpl(rw, r, a.manageAssetsURL(false))
	})
}